The modification of unsaturated polyesters with the esterifiable reactive hydrocarbon dicyolopentadiene is a well established technology. Typical of this art are U.S. Pat. Nos. 4,370,447; 4,100,120; 4,148,765; 4,224,430; 4,233,432 and 4,246,367. Dicyclopentadiene is sold commercially as a product of about 97 or greater percent purity. lt is also sold as C.sub.10 hydrocarbon concentrate prepared by dimerizing a crude C.sub.10 stream from the cracking of hydrocarbons as taught in U.S. Pat. No. 3,557,239. A preferred dicyclopentadiene source for use in modification of unsaturated polyesters is one that is low in peroxides and hydroperoxides and in light hydrocarbons and residual cyclopentadiene.
Dicyclopentadiene concentrates have as the main reactive component about 70 to 90 percent by weight of dicyclopentadiene and about 5 to about 30 percent by weight of mixed Diels-Alder dimers of diolefins such as butadiene, cis- and trans- piperylene, isoprene, cyclopentadiene and methyl cyclopentadiene. The remainder of these concentrates generally comprise residual C.sub.5 hydrocarbons and oligomers of the above diolefins. Examples of some of the dimers which have been identified in these concentrates are the Diels-Alder adducts of two moles of isoprene (isoprene dimers), the adduct of cyclopentadiene and isoprene, the adduct of cyclopentadiene and piperylene, and the like. These C.sub.10 hydrocarbon streams have very little or no ethylenically unsaturated aromatic hydrocarbons such as styrene. It is notable that the prior art teaches both the use of the C.sub.10 concentrate or the relatively pure dicyclopentadiene as sources of esterifiable hydrocarbon reactives for the modification of unsaturated polyesters.
More recently, modification of unsaturated polyesteramides with the aforementioned dicyclopentadiene or C.sub.10 concentrates has been described. Typical of this art are U.S. Pat. Nos. 4,410,686; 4,409,371 and 4,471,101.